Reverb's Power Transformer puts out 15 more volts than the Vibroverb. The B+ well beyond the Vibroverb levels because the Bandmaster Using a GZ34 like the Vibroverb will boost *Using a 5U4GA Rectifier tube will bump the B+ voltage up toĪB763 Vibroverb levels. In 1970 FenderĬhanged to a 10 times larger. The 500pF might be best for a slightly tighter overdrive tone. 001uF cap would probably be best, but if you use closed back cabs or If you play mostly clean or use mostly open backĬabs the. Trim some bass because the matching blackface extension cabs were closed backĪnd had extended bass response. With an asterisk because Blackface head amps used a 500pF coupling cap and theĬombo amps used a. *Note the Phase Inverter Coupling Cap is shown in red Preamp plates for a little less resistor hiss. I like to use 1 or 2 watt rated resistors on Replace the Phase Inverter Plate Load resistors with 82K (V6A)Īnd 100K (V6B) 1/2 watt resistors. The only other differenceīetween the AA270 and AA1069 is the AA270's 1k bias resistor and extra filter stage in the bias Phase inverter coupling cap compared to the AA1069. Phase Inverter Plate Load resistors are the mostĪll the Differences Between the AB763 Vibroverb and AA1069 Bandmaster Reverb Into a 1963 AB763 blackface Vibroverb with just a few I blackfaced my 1972 AA270 silverface Bandmaster Reverb (TFL5005D) Wires and control pot wires with red grounded wires for a "poor man's shieldedĬable" to reduce noise transmitted and received by these wire groups.ĭifferences between the AA1069 and AA270 are in pink. Note how Fender wrapped the doghouse power
I changed the couplingĬap to blackface standard. The only differences between the AA1069 and AA270īandmaster Reverb are the AA270's power transformer, biasĬircuit with 1k bias resistor, extra filter stage consisting of an additional 3.3k resistor and 50uF 70v filter capĪnd a 10x larger. My AA1069 Bandmaster Reverb Layout Created In DIYLCĬlick on the image to see the hi-res version. These are my bone stock AA270 Bandmaster Reverb voltages.
#Bias amp 2 upgrad mods
How much you can do with simple preamp tube swaps.ĪA270 Bandmaster Reverb Mods What I did to my sweet ass Power Tubes in a 4圆L6 Amp Cut your big amp's power by 65%. Tubes in a 4 Power Tube Amp Cut your output power almost in half. Output power, small bottle tone with more power tube distortion.Īmp A tone change with little power gain. Head Cab Make your head cab a little heavier but a lot more Reverb Dwell Control Mod Add more reverb control.
#Bias amp 2 upgrad mod
Preamp & Phase Inverter Voltage An excellent mod for amps upgraded Two identical tone stacks? Mod one of them. The tone stack and boost gain for a very tweedy tone. Use this late-in-the-circuit tone control to tame ice pick and tweak your tone. Pentode/Triode Switch Cut power tube output for lower volume In External Box External box goes between your amp and speaker to dump I loveĭump 3/4 of the amp output for lower volumeġ0% Power Switch Dump 90% of the amp output for true bedroom level outputġ0% Power Jack Use your Aux jack as a 10% output jack Mod Master volume AND late-in-the-circuit tone control. Trainwreck Type-2 or simple Type-3 PPIMV master volume. Something constructive with your unused Normal channel. Mod Apply reverb and tremolo to both channels the way Fender did Silverface Amp Make your silverface amp sound right )īias Balance circuit to Adjustable Bias + Bias Balance It's veryĬhannel Reverb Mod The preferred way to apply reverb and tremolo to both channels and This extra size allowed two 8" Fender Special
My very cool Fender AA270 silverface Bandmaster Reverb.įender made the head cab extra large to allow for distance between the power Is also a great place to mod away with to make that channel interesting and Mods that allow me to go back to the amp's original circuit and tone.
#Bias amp 2 upgrad full
"blackface" these amps for a full generational regression.
The silverface amps are surprisingly similar to the covetedįender blackface line of amps so many blackface mods and tweaks apply to the Princeton, Princeton Reverb, Champ, Vibro Champ, Showman and Vibrolux Reverb. The "1069" in the model name comes from the circuit change dateĭeluxe Reverb, Twin Reverb, Super Reverb, Pro, Bandmaster Reverb, Bassman, 'AA1069' was Fender's internal model designation for the 1969Ĭircuit. Use just one hand when working on a powered amp. Lethal shock can run between your arms through your heart. Never touch theĪmplifier chassis with one hand while probing with the other hand because a High voltage then have an amp technician service your amp. If you have not been trained to work with Tube amplifier chassis contains lethal high voltage even when unplugged-sometimes Have comments or corrections? Email rob at: robinette at
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